.TH LLOG_READER 8 2024-08-28 Lustre "Lustre Configuration Utilities"
.SH NAME
llog_reader \- lustre on-disk log parsing utility
.SH SYNOPSIS
.SY llog_reader
.I FILENAME
.YS
.SH DESCRIPTION
.B llog_reader
parses the binary format of Lustre's on-disk configuration logs.
It can only read the logs. Use
.B tunefs.lustre
to write to them.
.SH CAVEATS
Although they are stored in the CONFIGS directory,
.I mountdata
files do not use the config log format and will confuse
.BR llog_reader .
.SH EXAMPLES
To examine a log file on a stopped Lustre server, first mount its
backing file system as ldiskfs, then use
.B llog_reader
to dump the log file's contents:
.RS
.EX
.B # mount -t ldiskfs /dev/sda /mnt/mgs
llog_reader /mnt/mgs/CONFIGS/tfs-client
.EE
.RE
.PP
To examine the same log file on a running Lustre server, use the
ldiskfs-enabled debugfs utility (called
.B debug.ldiskfs
on some distros) to extract the file:
.RS
.EX
.B # debugfs -c -R 'dump CONFIGS/tfs-client /tmp/tfs-client' /dev/sda
llog_reader /tmp/tfs-client
.EE
.RE
.PP
To examine Changelog records on a stopped Lustre server, first mount its
backing file system as ldiskfs, then use
.B llog_reader
to dump the log changelog's contents:
.RS
.EX
.B # mount -t ldiskfs /dev/sda /mnt/mgs
.B # llog_reader /mnt/mgs/changelog_catalog
rec #1 type=1064553b len=64 offset 8192
Header size : 8192
Time : Mon Jan 22 23:28:24 2018
Number of records: 1
Target uuid :
-----------------------
\&#01 (064)id=[0x5:0x1:0x0]:0 path=
.I "O/1/d5/5"
.B # llog_reader /mnt/mgs/
.I O/1/d5/5
rec #1 type=10660000 len=136 offset 8192
rec #2 type=10660000 len=136 offset 8328
rec #3 type=10660000 len=128 offset 8464
Header size : 8192
Time : Mon Jan 22 23:30:01 2018
Number of records: 3
Target uuid :
-----------------------
\&#01 (136)changelog record id:0x0 cr_flags:0x9000 cr_type:CREAT(0x1)
date:'14:30:01.370700741 2018.01.22' target:[0x200000402:0x1:0x0]
cr_extra_flags:0x3 user:0:0 nid:10.128.11.159@tcp parent:[0x200000007:0x1:0x0]
name:fileA
.EE
.RE
.SH AVAILABILITY
.B llog_reader
is part of the
.BR lustre (7)
filesystem package since release 1.4.0
.\" Added in commit 1.3.4-1130-g113303973e
.SH SEE ALSO
.BR lustre (7),
.BR tunefs.lustre (8)
.P
Lustre Operations Manual,
.IR "Troubleshooting Lustre" .
